Road Markings.

[ferlew]

I have recently noticed, on the larger roads in my area, geometric shaped markings.
Barely noticeable if you're not looking.
Elongated diamonds, blocks of squares or oblongs, chevron shapes.
They look as if they have been applied with a large piping bag.
Does anyone have any ideas what they are?
Also, yellow roadsigns, with black borders, and large dots or other shapes inside, no writing on them. What on earth are they for?

[237SJ]

I have read about this but unfortunately, I just can`t remember where I read it. It might have been something that was in the newspapers.

[237SJ]

This is not strictly what you are looking for but I thought I would post it anyway http://www.bbc.co.uk/news/magazine-25915468

[vulcan42]

as scrivens says, some of the signs are for emergencies.
http://www.cbrd.co.uk/indepth/edr/

[ferlew]

Hmmm, when I asked locally, I was told they marked routes for refuse lorries, and lorries from the sewage farms. The ones I have been seeing are not near motorways. No words on them.

[whiskeryron]

Alien landings lol.

[Canary42]

Some motorways (e.g. M11) have (experimental) white chevrons at intervals on the road surface - they assist safe vehicle spacing - I believe you should always be able to see two sets of chevrons between you and the car in front, if not you're too close.

[ferlew]

Let me re iterate.
The boxes, chevrons, etc are ON the road surface, they appear to have been applied with liquid tar. They are not on the rural village roads, but on the roads entering my closest large town, (Hull).
The black/yellow signs are usually on lamp posts etc, on the more rural routes.

[ferlew]

No Scrivens.
Imagine an upside down OUTLINE of that, but wider.
All you can discern is a vague outline in what I presume to be tar.
Difficult to describe.

[sddsddean]

As Scrivens answer, in the trade we call them 'detector loops'. Basically you cut a slot in the tarmac about 2" deep woth a diamond edged circular saw, clean it out (usually with a hover mower, so if you see someone mowing the tarmac, they're not mad!) lay usually 3 loops of a wire in a rubber coating in the slot and then seal the whole lot with hot bitumen (not allowed to use tar now as it is a carcenogen). The ends of the wires are fed back to the control box for the traffic light system or whatever. A low current is passed through the loops. If a vehicle enters the loop, due to electro magnetic induction (sounding clever huh?!) the current increases. The control box detects this and knows there is a vehicle waiting to turn or whatever. Thats the theory and most of the time it works!!

[ferlew]

Scrivens, EXACTLY like that !
sddsddean, thanks for the full answer.
Now just the local yellow/black roads signs are still a mystery.

[ferlew]

Yes, thanks.